Inhibition of allergic reactions by a new antiallergic drug, LC-6 (trans-2,3b,4,5,7,8b,9,10-octahydronaphthol[1,2-c:5,6-c'] dipyrazole). I. Inhibition of the rat reaginic passive cutaneous anaphylaxis.

A new synthetic compound, LC-6, has been shown to inhibit the passive cutaneous anaphylaxis reactions induced in rats by mouse reaginic antibody. In this system, the ED50 was 35 mg/kg body weight of LC-6 administered per os. LC-6 prevented neither histamine skin reactions nor the reactions to histamine and other chemical mediators released by 48/80. Therefore, its inhibitory activity is comparable to that of the model anti-allergic compound, disodium cromoglycate (DSCG). In contrast to DSCG, the new drug exhibits the distinct advantage of being active per os and over prolonged periods of time. Its activity has been shown to persist for at least 6 h when doses 4 times higher than the ED50 were administered. The duration of the drug effect was clearly dose-dependent. Predoses of the compound increased its effectiveness. The long-lasting association of LC-6 with mast cells, as indicated by its prolonged inhibitory activity, makes it a valuable tool in the search for receptors involved in anaphylactic reactions.